Research on Waterflood Sweep Law in Low Permeability Vertical Heterogeneous Reservoir

Multi-layer heterogeneous reservoir commonly exist interlayer interference. It leads to low producing degree, low sweep efficiency and low waterflooding recovery. Vertical heterogeneity seriously affects efficient development of low permeability reservoirs. The waterflooding experiment of single core and core combined model were carried out in this paper. The influence of permeability ratio and the average permeability to the law of the waterflooding sweep were researched. Results show the measured water absorption of core combined model is in accord with theoretical formula of multi-layer heterogeneous reservoir. The displacement experiment of core combined model can accurately reflect the waterflood sweep law. As the permeability ratio is larger, the percentage of water absorption in high permeability gradually increases. When the permeability ratio is larger than 9, the injected water hardly sweeps low permeability layer. And thickness waterflood sweep efficiency increases quickly in low water cut stage.